Abstract: XENON100 is a dual-phase (liquid-gas) time projection chamber (TPC) containing a total of 161 kg of LXe with a 62 kg WIMP target mass, built with radiopure materials to achieve an ultra-low electromagnetic background and operated at the Laboratori Nazionali del Gran Sasso in Italy. Data from the XENON100 experiment have resulted in the most stringent limits on the spin-independent elastic WIMP-nucleon cross sections for WIMP masses above 8 GeV/c^2.

I will present the experiment and its latest dark matter search results. I will also discuss a dedicated test facility built and operated at Columbia University to measure with high precision the scintillation response of LXe to low-energy electrons and nuclear recoils of interest to dark matter direct detection experiments like XENON.